1. Field of the Invention
The present invention relates to fuels, particularly gasoline fuels which are substantially oxygenate free. More specifically, the present invention relates to a low-emission gasoline fuel which complies with the California Predictive Model, as well as ASTM D4814, and is also substantially oxygenate free.
2. Brief Description of the Prior Art
One of the major environmental problems confronting the United States and other countries is atmospheric pollution caused by the emission of pollutants in the exhaust gases and gasoline vapor emissions from gasoline fueled automobiles. This problem is especially acute in major metropolitan areas where atmospheric conditions and the great number of automobiles result in aggravated conditions. While vehicle emissions have been reduced substantially, air quality still needs improvement. The result has been that regulations have been passed to further reduce such emissions by controlling the composition of gasoline fuels. These specially formulated, low emission gasolines are often referred to as reformulated gasolines. California's very strict low emissions gasoline is often referred to as California Phase 2 or Phase 3 gasoline. In these gasolines, oxygen-containing hydrocarbons, or oxygenates, are often blended into the fuel.
Congress and regulatory authorities, such as CARB (the California Air Resources Board), have focused on setting specifications for low emissions, reformulated gasoline. The specifications, however, require the presence of oxygenates in gasoline sold in areas that are not in compliance with federal ambient air quality standards for ozone, and the degree of non-attainment is classified as severe, or extreme. Among the emissions which the reformulated gasoline is designed to reduce, are nitrogen oxides (NOx), hydrocarbons (HC), and toxics (benzene, 1,3-butadiene, formaldehyde and acetaldehyde). A reduction in these emissions has been targeted due to their obvious impact upon the air we breathe and the environment in general.
Oxygenated gasoline is a mixture of conventional hydrocarbon-based gasoline and one or more oxygenates. Oxygenates are combustible liquids which are made up of carbon, hydrogen and oxygen. All the current oxygenates used in reformulated gasolines belong to one of two classes of organic molecules: alcohols and ethers. The Environmental Protection Agency regulates which oxygenates can be added to gasoline and in what amounts. The ether compounds are of particular concern environmentally.
The primary oxygen-containing compound employed in gasoline fuels today are methyl tertiary butyl ether (MTBE) and ethanol. While oxygen is in most cases required in reformulated gasolines to help effect low emissions and the presence of ethanol has become more important, the presence of ether compounds such as MTBE in gasoline fuels has begun to raise environmental concerns. For example, MTBE has been observed in drinking water reservoirs, and in a few instances, ground water in certain areas of California. As a result, the public is beginning to question the benefits and/or importance of having cleaner burning gasolines, if they simply pollute the environment in other ways. Furthermore, oxygenates such as ethers also have a lower thermal energy content than non-oxygenated hydrocarbons, and therefore reduce the fuel economy of gasoline fueled motor vehicles.
Thus, while some of the concerns with regard to gasoline fuels containing ether could be overcome by further safe handling procedures and the operation of present facilities to reduce the risk of any spills and leaks, there remains a growing public concern with regard to the use of ether compounds in gasoline fuels. In an effort to balance the need for lower emission gasolines and concerns about the use of ether compounds it, therefore, would be of great benefit to the industry if a cleaner burning gasoline without ethers could be made which complied with the requirements of the regulatory authorities (such as CARB). The availability of such a gasoline, which contained substantially no ethers, would allow the public to realize the environmental benefits of low emissions, yet ease the concern of potential contamination of ground waters, and the environment in general, with ether compounds such as MTBE. Of benefit to the industry would also be the economics of such a low emission gasoline which contained substantially no ether compounds.
Accordingly, it is an object of the present invention to provide a gasoline fuel, and a method of blending same, which can truly benefit the environment and continue to be suitable for use as a motor gasoline.
Yet another object of the present invention is to provide such a gasoline fuel, and method of blending same, which is specifically suitable for the summer season, and of particular value a high octane summer fuel, which offers considerable difficulties in blending.
It is another object of the present invention to provide a high octane summer gasoline fuel, and method of blending same, which provides good emissions, yet is substantially free of ether compounds.
It is yet another object of the present invention to provide an economic and commercially plausible method for blending such a summer gasoline fuel.
These and other objects of the present invention will become apparent upon a review of the following specification, the Figures of the Drawing, and the claims appended hereto.